Some things you might think about for a little while....
One can have and love friends without dating and sleeping with them. Polyamorous, monogamous, whateverous, you can certainly have and love your friends. Infatuation happens. And it happens to pretty much everyone. That doesn't mean you have to act on it. It isn't cheating to hit it off with a friend and become closer/better friends. You don't have to hop in the sack with someone just because you're infatuated with them.
If you DO feel like a romantic love with multiple partners might be something you could enjoy, consider whether it is something you need, or if you would be comfortable - not hesitantly okay, not reluctantly tolerant, but truly comfortable - with keeping those potential lovers as "just" friends, and remain monogamous for the sake of your monogamous partner. I know I wouldn't, but a ton of people can and do, and you might be one. "Just" friends is almost a dirty word - friends are *beautiful*, and the gift of friendship with someone you are able to grow to love is made no less beautiful by not dating them.
I, personally, feel like you kind of owe it to your boyfriend to be honest and open about every aspect of your relationship with him, and that includes these romantic feelings that keep popping up. Maybe he'll think about it and conclude that he might want to give the "poly thing" a shot. Maybe he will be okay with certain things but not others. Maybe he won't be okay with it at all.
You definitely need to consider how he's going to feel about this before you try to discuss it with him, however, and what you ultimately want in your relationship with him. You mention that he's having a tough time with life right now, and you obviously know you need to be gentle with him. If you can understand yourself a bit better before you talk to him about it, that'd be awesome, but if not, be sure to be clear with him that you *don't* know what you want/need, if that's the case.
Some important questions to ask yourself:
Do you sincerely feel that you need to act on these romantic feelings to be complete or true to yourself?
If you find yourself falling in love with a friend, would you be comfortable being (here's that dirty word again!) "just" friends? Would doing so make you feel any resentment toward your partner?
What does your perfect relationship model look like? And where in that ideal are you willing to make compromises? What are the things you NEED, versus the things you WANT?
If you tell your boyfriend about these feelings and he's sorely hurt over it, what do you think you will do? Consider the worst-case scenario and prepare for it, so you can be as gentle as possible for him.
There's a lot more to love than whether you'd give him your, uh, your car or life (since the two are so interchangeable? Uhh, not sure where PaulFromN.O. was coming from on that.... or anything else, really....) without hesitation. There's honesty, openness, acceptance, compromise.... Respect, admiration.... So much more than romance.